Electric heater-reflector assemblies



May l, 1962 R. c. HALL ELECTRIC HEATER-REFLECTOR ASSEMBLIES Filed Feb. 24. 1959 may United States Patent Office 3,032,638 Patented May 1, 1962 3,032,638 ELECTRIC HEA'IER-REFLECTOR ASSEMBLIES Richard C. Hall, Verona, Pa., assignor to Edwin L. Wiegand Company, Pittsburgh, Pa. Filed Feb. 24, 1959, Ser. No. 795,201 Claims. (Cl. 219-34) The present invention relates to radiant heaters, more particularly to radiant electric heater-reflector assemblies f of the type for effecting a desired pattern of heat distribution on material to be heated, and the principal object of the invention is to provide new and improved devices of such character. Y

In the past and especially when heating strip material by means of radiant heat, it has been diiiicult to achieve even heating from edge to edge of the material since its center tends to become heated more than its edges. This apparently results for two reasons: Firstly, the center tends to receive a greater amount of effective radiation than do the edges. Secondly, heat is dissipated more quickly from the edges of the material than from the center and this heat loss tends to lower the temperature of the edges.

A common and quite satisfactory arrangement for the heating of longitudinally moving strip material, apart from the disabilities above mentioned, has been to dispose an elongated, electric radiant heater-reilector assembly adjacent the side of the material to be heated and extending transversely thereof so as to direct heat from edge to edge of the material.

The present invention contemplates a heater assembly ofthe general type above mentioned, however, this assembly utilizes a plurality of highly eicient, long lived, low cost, tubular metallic sheathed electric resistance heating elements arranged in a suitable reflector to provide the desired heat distribution on the material to be heated. The advantages of the present invention will readily become apparent from a study of the following description and from the drawings appended hereto.

In the drawing accompanying this specification and forming a part of this application there is shown, for purpose of illustration, an embodiment which the invention may assume, and in this drawing:

FIGURE l is a perspective view of a preferred embodiment of the invention, facing downwardly to direct heat upon underlying strip material (not shown) or other body,

FIGURE 2 is an enlarged, broken, bottomside View of the assembly seen in FIGURE 1,

FIGURE 3 is a further enlarged, fragmentary sectional view generally corresponding to the line 3 3 of FIG- URE 2,

FIGURE 4 is an enlarged sectional view generally corresponding to the line 4 4 of FIGURE 2, and

` FIGURE 5 is anenlarged, broken, sectional view of a type of heating element employed by the present invention during an intermediate stage of manufacture.

As seen in the drawing, the present invention comprises two major components: First, an elongated, channel-like reilector member which, for convenience, may be made by an extrusion process and a plurality of electric resistance heating elements 11, 12 and 13, preferably of the tubular, sheathed, embedded type, mounted within the channel opening of the reflector.

As best seen in FIGURE 4, rellector member 10 has opposed, inwardly directed, longitudinally extending lips 14 on each side of the channel opening for retaining within such opening and in conformity with the defining wall thereof, a strip of highly reflective metal or other material which extends substantially the full length of the reflector. Such lips also serve another purpose as will later appear.

plan

It is an important feature of the present invention that the heating elements 11, 12 and 13 are of the metallic, tubular sheathed embedded type. With reference to FIGURE 5, each element preferably comprises a coiled resistor conductor member 16 disposed within the intermediate portion of an elongated tubular metallic sheath 17. Respective ends of the resistor terminate short of respective ends of the sheath and, for the purpose of conducting electrical energy to the resistor, respective ends thereof are electrically connected with terminal pins 18, each of which projects beyond a respective sheath end to permit the necessary electrical connection to be made thereto. The free ends of the terminal pins may, if desired, carry any suitable lugs or the like to facilitate connection of the current supply wiring thereto. The interior of the sheath is preferably filled with electric-insulating, heat-conductive material 19 compacted to rock-like hardness by exerting transverse pressure upon the filled sheath. It is to be understood that each of the elements is usually manufactured in the rectilinear form seen in FIGURE 5 and thereafter bent, as will be disclosed, to provide the desired configuration.

For obvious reasons, the intermediate portion 20 of the heating element seen in FIGURE 5, that is, that portion of the element adjacent the resistor conductor 16, is known as the heat-generating element portion while the element portions adjacent the terminal pins 18 are known as terminal end portions.

Heating element 11 of the present invention, and also element 13 since it is preferably identical to element 11, is formed by doubling a rectilinear element such as seen in FIGURE 5 back on itself to a U-shaped configuration with respective terminal ends 21 of the element in side by side relation spaced from the bight 22 at the other end of U-shaped contigurated element.

Each element 11, 13 is disposed at a respective end of the reflector 10 within the channel opening thereof to extend longitudinally of the reflector. Such elements are disposed within the reector as seen in FIGURE 2 with their bight portions 22 in spaced, facing relation and with their terminal end portions at respective extreme ends 0f the reflector.

Any suitable means may be employed for holding element 11 in position within the reiiector. For example and as shown in FIGURE 3, a split, dielectric body 23 may be clamped over the terminal end portions of the element by means of a screw 24. A bracket 25 may be secured to the body by means of the screw 24 and to the reflector by means of a screw 26 to thus support the terminal end portions of this element. One of the element terminal portions may be provided with iixedly positioned, spaced collars 27 which straddle body 23 and limit relative movement between the body and the element. It is to be noted that the foregoing element supporting arrangement disposes the heat-generating portion 20 of element 11 on one side of the body 23 and the projecting ends of its terminal pins 18 on the other side of the body. A plate 28 may be carried by body 23 to overlie the reflector channel opening adjacent the element terminal pins to provide with the reflector channel a compartment which encloses the electrical connections between the current supply wiring (not shown) and the terminal pins. v

The means provided for supporting the bight portion end of the U-shaped element 11 may comprise a sheet metal bracket 29, see FIGURES 2, 3 and 4, slotted at 30 to receive split, dielectric bushings 31 which are apertured to slidably pass respective legs of the .U-shaped element. A retaining wire 32 may removably hold bushings 31 assembled with the bracket. As best seen in FIGURE 2, bracket 29 is formed of two pieces of sheet metal welded or otherwise secured together in side by side rela- .ae-sacas tion and respective adjoining pairs 33, 34 of the ends of Such pieces are spread apart to rest upon the previously mentioned lips 14 of the reflector.

Since elementi13 is identical to element 11 and is supported in an identical manner, the foregoing decription directed toward element lill will sullce for an understanding of element 13 and its mode of support.

Turning now to heating element 12, this element may be similar to that seen in ElGURE 5 however, it differs from the elements 11 and 13 in that its heat-generating portion 2t) is doubled back on itself to provide a'pair of legs 35, 36 (see FIGURE 2) in side by side relation connected together at adjoining ends by respective bight porv tions 37. As illustrated, element 12 extends longitudinally of the reflector and is disposed within its channel opening with respective bight portions 37 thereof adjacent the bight portions 22 of respective elements 11, 13.

The terminal ends 21 of element 12 preferably extend in side by side relation from leg and in a direction transversely thereof to project through respective enlarged apertures 38 (see FIGURE 3) formed in the reflector 1t) and in the reflective strip .15. The free ends of the element terminal ends are disposed within a sheet metal box 39 which is carried by the reflector and which encloses the electrical connections between the current supply wiring (not shown) and the terminal pins.

'Dielectric sleeves 40 are disposed over the terminal ends 21 of the element 12 to insulate this element from the reflector at the point where it passes through apertures 38. These sleeves have enlarged heads 41 which rest upon the upper surface of the reflector to retain the terminal ends of the element in position within box 39. To retain the sleeves y assembled with the element terminal ends, terminal pins 118 may be threaded to receive nuts 42. Suitable Washers 43 may be interposed between the Washers and a respective sleeve to complete the assembly. For a'purpose to be seen, apertures 38 are larger than the shank portions of sleeves 40 to permit limited transverse movement of the element terminal ends relative to the reflector.

Means are provided for supporting each end of element 12 adjacent its bight portions 37, such means preferably comprising bracket assemblies 44 identical to the previously described bracket 29 and its associated parts. The apertures in this bracket assembly through which pass respective elementlegs 35, 36 are slightly larger than the transverse size of respective legs to provide for longitudinalr movement thereof.

It will be understood that since bracket 29 slidably supports the bight end of element 11, the latter may freely expand and contract longitudinally during its heating and cooling cycles. The same is true of element 13 since the latter and its mode of support is a duplication of element 11. It will also be understood that the bracket assemblies 34 and the oversize apertures 38 in the reflector and reflecting plate permit similar expansion and contraction of the element 12 during heating and cooling cycles.

To provide the desired heat distribution with the present heater-reflector assembly, itis only necessary to choose heating element having the requisite heat output. For example, when strip material is to be evenly heated, the end heating elements 11 and 13 will preferably have a higher heat output per unit length of element than the intermediate element 12 so that the greater heat output at the ends of the assembly will counterbalance the edge losses of the strip material.

While-the use of heating element having different heat outputs as above described is simple and low in cost, certain applications require a more flexible arrangement. In such cases, all of the elements may have the same heat output per unit length of element and the heat output of the intermediate element reduced as required by means of a suitable current input controller.

In view of the foregoing it will be apparent to those skilled in the art that I have accomplished at least the principalY object of my invention and it will also be apparent to those skilled in the art that the embodiment herein described may be variously changed and modified, without departing from the spirit of the invention, and that the invention is capable of uses and has advantages not herein specifically described, hence it will be appreciated that the herein disclosed embodiment is illustrative only, and that my Yinvention is not limited thereto.

AI claim:

l. An elongated radiant heater assembly comprising an elongated, trough-like reflector together with lirst and seoond heating element means carried by said reflector and provided by elongated, tubular sheathed electric resistance heating elements each having an intermediate heat generating portion and each also having terminal end portions for conducting electrical energy to its heat generating portion, said first element means comprising a pair of such heating elements each doubled back ony itself to a U-shaped configuration to dispose respective terminal end portions of each element in side by side relation spaced from the bight of said U-shaped configuration and each element of said pair being supported at a respective end of said reflector with the heating element bight portions in spaced, facing relation, said second element means comprising a single such heating element having its intermediate portion doubled back on itself to provide a pair of bightv portions in spaced, opposed relation and having its terminal end portions disposed in side by side relation intermediate its bight portion pairs, said heating element of said second element means being supported at an intermediate portion of said reflector with its bight portions adjacent respective adjoining bight portions of respective elements of said element means,

2. An elongated radiant heater assembly comprising an elongated, trough-like reflector having an apertured portion intermediate its ends, a pair of heating relements spaced longitudinally of said reflector from each other and supported at respective reflector ends, and an elongated, tubular sheathed electric resistance heating element having an intermediate heat generating portion and terminal end portions for conductingV electrical energy to said heat generating portion, said intermediate heat generating portion being doubled back on itself to provide an elongated heating body having looped end portions and having its said terminal end portions extending in side by side relation transversely of said body intermediate its looped end portions, said body extending longitudinally of said reflector between the elements of said pair and with its looped end portions adjacent respective such elements and with said terminal end portions through `said Iapertured reflector portion.

3. An elongated radiant heater assembly comprising an elongated, trough-like reilector having an apertured port-ion intermediate its ends, first and second heating element means carried by said reflector and provided by elongated, tubular sheathed electric resistance heating elements each having an intermediate heat generating portion and each also having terminal end portions for conducting electrical energy to its heat generating portion, said first element means comprising a pair of such heating elements each having its heat generating portion doubled back on itself to a U-shaped configuration to dispose respective terminal end portions of each element in side 1by side relation spaced from the bight of said U-shaped conliguration and each element of said pair being supported at a respective end of said reflector with their bight portion in spaced, facing relation, said second element means comprising a single such heating element having its intermediate heat generating portion doubled back on itself to provide an elongated heating body having looped end portions and having its terminal end portions extending in side by side relation transversely of said body intermediate its looped end portions, said second element means body extending longitudinally of said reflector between the elements of said pair and with its looped end portions adjacent the bight portions of respective elements of said pair and with its terminal end portions through said apertured reflector portion, and means supporting the heat generating portions of respective heating elements for movement longitudinally of said reflector to provide for free expansion and contraction of such elements during heating and cooling cycles thereof.

4. Au elongated radiant heater assembly comprising an elongated, trough-like reector having an apertured portion intermediate its ends, a pair of heating elements spaced longitudinally of said reflector from each other and supported at respective reflector ends, an elongated, 'tulbular sheathed electric resistance heating element having an intermediate heat generating portion and terminal end portions for conducting electrical energy to said heat generating portion, said heat generating element portion being doubled back on itself to provide a pair of legs in side by side relation connected together at adjoining ends by respective bight portions and said terminal end portions extending in side by side relation transversely of an intermediate portion of one of said legs, said sheathed element having the legs of its heat generating portion extending longitudinally of said reflector between the elements of said pair with its bight portions adjacent respective such elements and with its terminal end portions through said apertured refiector portion, Iand means supporting the legs of said heat generating element portion for movement longitudinally of said reflector to provide for free expansion and contraction of such element during heating and cooling cycles thereof.

5. An elongated radiant heater comprising an elongated, trough-like reflector having a portion intermediate its ends providing enlarged aperture means, first and second heating element means carried by said reflector and provided by elongated tubular sheathed electric resistance heating elements each having an intermediate heat generating portion and each also having terminal end portions for conducting electrical energy to its heat generating portion, said first element means comprising a pair of such heating elements each having its heat generating portion doubled back on itself to a U-shaped configuration to dispose respective terminal end portions of each element in side by side relation spaced from the bight of its U-shaped configuration and each element of said pair being supported at a respective end of said reflector with their bight portions in spaced, facing relation, said second element means comprising a single such heating element having its heat generating portion doubled back on itself to provide a pair of legs in side by side relation connected together at adjoining ends by respective bight portions and the terminal end portions of such second element means extending in side by side relation transversely of an intermediate portion of one of said legs through the enlarged aperture means of said refiector and having limited movement longitudinally thereof, said second element means having its heat generating portion extending longitudinally of said reflector between the elements of said pair with its bight portions adjacent the bight portions of respective elements of said pair, and means supporting the heat-generating portions of respective heating elements for movement longitudinally of said reflector to provide for free expansion and contraction of such elements during heating and cooling cycles thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,088,728 Stranszky Aug. 3, 1937 2,495,513 Doyle Ian. 24, 1950 2,668,896 Husaczka et a1 Feb. 9, 1954 2,688,685 Goodell Sept. 7, 1954 2,748,247 Kozhelt May 29, 1956 2,834,861 Temple May 13, 1958 2,839,659 Cotts et al June 17, 1958 2,877,332 Senior Mar. 10, 1959 2,917,616 Thomson Dec. 15, 1959 

